Missing ttp:contentProfiles in examples.

[skynavga]

Even though ttp:contentProfiles is recommended for all documents (SHOULD be present), it is absent from a number of examples that contain a tt element. Some of the examples where it is missing have ttp:profile from an older version of the specification, which raises the question of whether both ttp:profile and ttp:contentProfiles should be present in all the examples.

[palemieux]

I have reviewed the use of ttp:profile in examples, and propose changing it to ttp:contentProfiles in two instances at #507.

The other instances of the use of ttp:profile are in examples related to (a) features that are deprecated in versions of IMSC that introduced ttp:contentProfiles or (b) refer to other profiles of TTML that do not support ttp:contentProfiles. In such cases, I suggest keeping ttp:profile to avoid compatibility issues.